Just cut it back to the edge of the pot come spring. If you do it now the sap will flow out of the cuts further weakening a stressed plant. Before cutting it back allow it to get new growth then cut back to healthy growth. I always allow them to drop their leaves before preparing them for winter storage. How cold does your garage get? If it gets below 38F you might want to put it in the basement. Remember to keep it moist but not sopping wet, if it drys to the point that the soil shrinks away from the pot it is way too dry.

Thank you for responding to my question. For now, it's in the garage, and I didn't cut it back because I wasn't sure that was a good idea. So far, I'm sure it hasn't been anywhere near 38 degrees in our garage. If it gets really cold this winter, I'll move it into the basement. As for cutting it back, I'll wait until spring, as you suggest. Can I assume from what you're saying that it's probably still OK? Like I said, it hasn't been exposed to any really punishing cold, but it has been lightly frozen and has lost its leaves and flowers.

hi if i was you i would cut your plant back to about 3inches from the base it sounds to me that the frost has got hold of the plant and if your not carefull the frost will work its way down to the root ball if your plant had been frost free then cuting back in the spring would do fine i cut all my tryphla down in october and start them growing straight away so by christmas they are about ten inches in height and growing well i only keep the greenhouse frost free and this works for me good luck ps i only keep the compost moist not wet.

I've attached a link to the FAQ for this forum that discusses overwintering tender or basket fuchsias. You shouldn't have anything to be concerned about as one or two light frosts are generally recommended to force the plant into dormancy. You DO want to defoliate it (remove all the leaves) however and cut it back to 4-6 inches now. Water well before storing and keep above freezing.....35-40F is ideal. Much higher than that can stimulate the plant out of dormancy. It doesn't require any light during its dormant period so a garage, crawl space or unheated basement could work well as long as they generate proper temperatures.

Here is a link that might be useful: FAQ - Overwintering fuchsias